Features: Add cxx_override.

Help/variable/CMAKE_CXX_KNOWN_FEATURES.rst

@@ -32,6 +32,11 @@ The features known to this version of CMake are:
 
   .. _N2928: http://www.open-std.org/JTC1/SC22/WG21/docs/papers/2009/n2928.htm
 
+``cxx_override``
+  Override control ``override`` keyword, as defined in N2928_.
+
+  .. _N2928: http://www.open-std.org/JTC1/SC22/WG21/docs/papers/2009/n2928.htm
+
 ``cxx_static_assert``
   Static assert, as defined in N1720_.
 

Modules/Compiler/GNU-CXX-FeatureTests.cmake

@@ -6,6 +6,7 @@ set(_oldestSupported "(__GNUC__ * 100 + __GNUC_MINOR__) >= 408")
 set(GNU47_CXX11 "${_oldestSupported} && __cplusplus >= 201103L")
 set(_cmake_feature_test_cxx_delegating_constructors "${GNU47_CXX11}")
 set(_cmake_feature_test_cxx_final "${GNU47_CXX11}")
+set(_cmake_feature_test_cxx_override "${GNU47_CXX11}")
 # NOTE: C++11 was ratified in September 2011. GNU 4.7 is the first minor
 # release following that (March 2012), and the first minor release to
 # support -std=c++11. Prior to that, support for C++11 features is technically

Source/cmMakefile.cxx

@@ -46,6 +46,7 @@
   F(cxx_constexpr) \
   F(cxx_delegating_constructors) \
   F(cxx_final) \
+  F(cxx_override) \
   F(cxx_static_assert) \
   F(cxx_variadic_templates)
 

Tests/CompileFeatures/cxx_override.cpp

@@ -0,0 +1,7 @@
+
+struct A {
+  virtual void doNothing() {}
+};
+struct B : A {
+  void doNothing() override {}
+};